What guided tour? You can easily do Montreal on your own just riding the metro with a guide book. It's my favorite city in the world and I never had any tours. Read about the city and pick the sites yourself. You can do a lot of sight seeing by walking on your own. Stay near St Catherine street and from there take metro. My very first weekend was like that. Just go to places you want to see. It's a lot of fun to do Montreal on your own.